I think Ohmwrecker suffers from two problems:
The first is the one that Maple Nectar brought up- its too often outclassed by other things, and rarely necessary or interesting.
I think that the second is that Ohmwrecker has the wrong stats: It is a tank item, but it is clearly meant for divers.
Statwise, I think it is interesting. It is comparable to other HP/ Armor items, has the amazing Point Runner passive, but has less armor and health than the others in exchange for some HP. If its stats were brought up to par, even a little, it might become viable. However, based on how Divers are defined, it should probably have a mix of offensive and defensive state, of the sort that Divers will want, maybe attack speed or armor pen. What with Xin and Eve on the loose, and hopefully Aatrox coming along, there is a great opprotunity for Ohmwrecker coming.
It might also benefit from the Sunfire/ Thornmail treatment. Give it a mini-component so that it can be built earlier. Perhaps an item that blocks one tower shot on you ever 45 seconds?
I like the item from a theorycrafting perspective, and I think that its particle is really cool, so I hope that it sticks around.
Cheers,
-Nixtarma